Motor tester



Jan. 9, 1945. v.-| .wESTBERG Irl-Al.l

2,366,889 MOTOR TESTER I Filed Fem e, 1942 I 8 sheets-sheet 1 Jan. 9,1945.

v. I WESTBERG ET A1.

MOTOR TESTER Filed Feb. 6, 194g Jan- 9, 1945- v. L.. WESTBERG ET Al.2,366,889

MOTOR TESTER Filed Feb. 6, 1942 8 Sheets-Sheet 3 Jan. 9, 1945. v. L,WESTBERG ET AL MOTUR TESTER Filed Feb. 6, 1942 8 Sheets-Sheet 4 Jan- 9,1945- v. WESTBERG ET AL 23665889 MOTOR TESTER Filed Feb. 6, 1942 8SheetsSheet 5 W sf; f

Jan. 9, 1945. v. L.. wEsTBl-:R ET AL.

MOTOR TESTER Filed Feb. 6, 1942 8 Sheets-Sheet -6 Jan. 9, 1945. v.LJWESTBERG ET AL MOTOR TESTER Filed Feb. e, 1942 8 Sheets-Sheet 7 lln@Www www@ Jan. 9, 1945. v. L. WESTBERG ET Al. 2,366,889

MOTOR TESTER I Filed Feb. 6, 1942 8 Sheets-Sheet 8 Patented Jan. 9, 1945Moron TESTER Vivian L. Westberg, Arthur N. Nilsen, and Vernon C.Westberg, Chicago, Ill., asslgnors to John R. Tapp and Otto L. Rhoades,a copartiership doing business as Sun Manufacturing Application February.6, i942, serial No; '429,822

s claims. (ci. 177-311) This invention relates to analyzing devices forinternal combustion engines and more particularly to a compact portabletester for automobile and airplane engines or the like, wherein anumsystem, such as its distributor, may bodily be removed frorn theengine and may independently be operated by such drive at selectedspeeds while tests are being conducted thereon. Associated with thevariable drive mechanism is a stroboscopic apparatus to enable accurateanalysis of each phase of the distributors operation and synchronizationof the operation of the respective parts.

The novel stroboscope and mechanism asso- Vdetection of defectivedistributor cams, breaker points, vacuum advance, or vacuum brake, and

ber of interrelated testing instruments are cominstantly indicates anyinaccurate setting, timbinedin a common structure and employ a coming,or operation of such related devices. mon electrical arrangement. Thepresent inven- All required ignition characteristics of an ention isalso capable of continuous operation over gine operating at variousspeeds may be deteran extended period of time for running in or mined bymerely completing a single circuit conbreaking in distributors ofvarious types under neetiun from the analyzer Athrough thedistribpredetermined conditions of operation. utor, or the operatingcharacteristics of the dis- Various testing instruments have heretoforetributor alone may be determined by mounting been proposed toelectrically indicate specific enthe distributor on the synchronizer foroperation gine characteristics such as distributor cam thereby atvarious speeds and completing the sindwell, motor speed, distributorsynchronization, 15 gle circuit connection through the distributor inetc. However, such instruments must be indethe same manner as in testinga distributor aspendently connected to and operated solely by sembled onand operated by an engine. The the ignition system of the engine undertest and circuit connection in either case is preferably therefore theOperation Of the engine may be accomplished by means of only twoextension impaired S0 aS t0 make the 'Gest results Vary 2 conductorseach provided with a terminal clip so Substantially from the true normalOperation 0f that one conductor may removably be connected the engine-.Such independent units musi' be to the primary terminal vof thedistributor and separatiiy' and not concurrently Connected t0 the otherconductor grounded either on the enthe engine under tesi gine or on thesynchronizer, as the test may It is therefore an object to provide adevice require. Y for tesi-'ing eithei an Operating eiigim? or a sepaFurther objects will be apparent from the specrate distributor, in whichthe testing instruments ication and the appended c1ams are controlledby, but energized independently In the drawings: 1 giglsgucdg il; engineor of the Fig. 1 is a perspective view of an assembled It engineanalyzer unit illustrating one embodiment is also an obJect to provide acombustion of the invention. ignceo Zhir'gigg eraf Fig. 2 is a detailvertical sectional view taken distributor to be tested may be employedto operon ghe. Vermeil? Geniaal .tralnsverse plaine of the ate aplurality of indicating devices, which deem .Odlmfint s own in Fig' .tvices may be operated independently or concur- Flg' 1s a plan View ofthe syflcmomzfer um rently for-true analytical comparison of thereadtake?! m ihe direction of the anow m Flgg a ings of each test.portion being broken away for purposes of illus- A further object is toprovide an analyzer by tration' l which accurate engine operation testsmay be 40 Fig' is i" back View of the Synchronizer mt made of an enginewhile the engine is in actual Shown iii Fig- 2 and 3; operation andwithout affecting orimpairing the Fig' 5 is a Side elevation of theiiexibie Coupimg normal operation thereof. for driving 3' distribuioi'-The present invention includes variable drive Fig- 6 is an axiaiSectional Vie W through the means whereby a portion of an engineselectrical hoiioW Stub Shaft of the synchronizen Fig. 'I is a detailsectional view through one of the protractor ring supports and is takenon line 11 of Fig. 3.

Fig. 8 is a schematic electrical circuit diagram showing theinterrelated circuits for the stroboscope, tachometer, and dwell meter.

Fig. 9 is a schematic diagram showing a circuit for use in connectionwith a single instrument as a combined tachometer and dwell meter.

FEL 10 iS a diagrammatic development of a of the hubabove the discmultipole five-position switch for controlling the testing circui Fig.11 is an axial sectional view through a preferred form of friction drivemechanism for the stroboscopic disc.

Fig. 12 is a fragmentary face view of the ball supporting rotor shown inFig. 11.

Fig. 13 is a side elevation of the ball retaining disc shown in Fig.-11.

Referring to the drawings in detail, the embodiment illustratedcomprises a portable cabinet or the like A, on which is supported threeinclined panels I, 2, and 3. An electrically operated tachometer 4, acam dwell meter 5, and a control section 8 are mounted on the left-handside panel I. 'I'he right-hand side panel 2 supports a vacuum gauge 1, avacuum pump and motor assembly 8, and a control section 9.

A stroboscopic syn-chronizer is mounted on the central panel 3 and isprovided with a holding and operating unit for a distributor to betested. A distributor D is shown mounted in testing po sition in Fig. land is also shown in dotted lines in Fig. 2. The driving mechanism forthe synchronizer includes a motor and avariable speedtransmission bywhich the distributor may be operated at selected speeds.

The structure and operating mechanism of the synchronizer are moreclearly shown in Fig. 2, wherein the panel 3 is provided with anangularly displaced central lportion i preferably inclined approximatelyforty-five degrees from the verti cal and having a large round centralopening -I i.

The synchronizer unit is mounted inthe opening II and comprises a baseplate I 2 secured to the portion I3 of the panel. The back of the baseI2 is provided with reinforcing ribs i3 and depending motor supportingbrackets i4. The base plate I2 also has an upstanding circular ange I5,which flange is concentric with an integral depending bearing hub orboss t3 for supporting a driven hollow stub shaft i 1. The lower end ofthe stub shaft is rotatably supported by suitable ball bearings I 9andis provided adjacent its free end with. a socket I9 to receivevarious interchangeable split collets or the like, each collet beingadapted to receive therein the end oi a corresponding type ofdistributor shaft. A

setscrew 20 is provided to clamp the collet to a distributor shaft andsimultaneously lock the collet in the socket so that the distributor maybe positively driven from the shaft I'l.

The shaft Il has a hub 2l, which hub may be a press llt on the shaft tosecure it for rotation therewith. Securely bolted to this hub forrotation therewith is a fiat circular disc or stroboscope plate 23. Alsoforming` an integral part 23 is a dlshed stroboscope tube housing 24,the entire assembly being adapted for rotation as a unit with the shaftIl. The back surface of the disc 23 also functions as a friction.surface whereby the disc and distributor may be driven at any requiredspeed by means of a variable speed friction drive transmission whichwill be described later. f v

Secured to the upper end of the hub 2| is a coaxial flexible coupling(Figs. 2 and 5) comprising a flexible ring 26 secured to the hub atdiametrically opposite points and secured to a coupling sleeve 2'I atdiametrically opposed in-I termediate points. The upper end of thissleeve Fig. 2 so that its the socket is rotated thereby in a manner toaccommodate slight inaccuracies in the alignment of the parts.

The dished stroboscope tube housing 24 is provided with a neon or thelike iiash'tube 29 mounted therein in any suitable manner as shown inflash rays will pass through an adjacent lens mounted in the wall of thehousing andwill be directed upon an arrow or other suitable indicia 3i(Figs. 2 and 3) upon the disc 23, the arrow being in iixed alignmentwith the lens.

The arrow' 3| is tion of the disc 23 faced to reflect incident lightrays. As the disc 23 and housing 24 rotatetogether. as a unit.

preferably an embossed porthe lens 30 is always opposite the arrow and,y

upon an instantaneous flash of the stroboscope tube, the moving arrowappears tothe eye of an observer to stand still at the precise pointWrere the ash occurs.

The tube housing 24 is also provided with an outwardly and downwardlyextending peripheral shade flange 32 so that stray light from the lenswill not strike the eye of the observer.

The stroboscope tube housing 24 is also provided With an upstandingcontact brush 33,

21 is Asecured to an intermediate portion of a which latter may be acarbon brushvr other sultable contacter forming a part of an electricalcircuit for controlling thetube. The brush is in constant wiping contactwith a contact ring 34, which latter is secured to an insulating plate33, the plate, in turn, being secured to an overhanging xed cover member38. The cover member 33 is provided with an axial opening through whichthe distributor collet socket I9 projects and which opening issumciently large to permit the necessary ection of the universalcoupling and socket when the device is in operation.

The neon or other gas type flash tube 29 previously mentioned isprovided .with an external trigger grid and the trigger terminalls'electrically connected in series with the brush 33, contact ring 34,and a conductor 31 connected to the contact ring 34 and extendingunderneath thev supporting arm 33a of the fixed cover member 36. Aconductor 33 is connected to a terminal of the neon tube, the otherterminal of the `tube being grounded. The conductor 3s passes throughthe hollow stub shaft I'I and is pro# vided with a contact terminal 33extending from the bottom of the shaft and insulated therefrom,

as shown in Fig. 6. A resilient brush 40 (Figs.

2 and-4) is fixed on insulated supports secured -to the base plate I2and in constant electrical contact with the rotatable terminal 39. The

brush 40 forms a continuation of the conductor A 38 and iselectricallyconnected to a loading condenser for the neon tube as willlater be described in connection with the electrical circuit shown inFig. 8. The electrical connections just described form part oi' anelectrical testing circuit for flashing the neon tube and this circuitwill be described in detail later.

. A vertically adjustable distributor supporting arm 4I (Figs-2 and 3)is slidably supported onv guide rods 42'by means of bearing portions 43.'I'he vertical adjustment permits the mounting of' various types ofdistributors on the synchronizer. The free end of thissupporting arm isprovided with a distributor supporting opening 44' in axial alignmentwith the socket I9 so that the shank of a distributor housing D may beinserted therein and secured by means of a thumb as shown and issuitably surscrew44a as shown by dotted lines in Fie. 2. The guide rods42 are supported in and extend outwardly from the base I2 and areparallel to the axis of the stub shaft I1 so that, at all positions ofvertical adjustment, the shaft of the distributor being tested ismaintained substantially in axial alignmentwith the stub shaft I1.

The guide rods 42 are joined at their upper ends by a cross bar 45. Anadjusting screw 46 is rotatably mounted on the cross bar 45 and threadedthrough an opening 41 in the arm 4I so that the arm may be raised andlowered on the guide rods by manually operating a crank handle 48secured to the outer end of the adjusting screw.

The variable speed drive mechanism by which the stub shaft I1 andassociated parts, including the driveshaft of a4 distributor under test,are rotated, comprises a reversible constant speed motor 49 (Fig. 2)having a friction cone 50 secured to the motor shaft. The motor 43 ispivotally suspended on the depending bracket arms I4 of the base I2 .bymeans of a motor bracket I4a on the motor so that the motor shaft andthe stub shaft I1 are in the same vertical axial plane but angularlydisposed relative to each other'as shown. The friction cone 50 ispositioned 'so that its driving surface is substantially parallel to theunder surface of the stroboscope disc 23, which latter also functions asa friction disc. An idler friction roller I is mounted between thefriction cone 50 and the stroboscope disc 23 and is preferably formed ofrubber or the like to secure a suitable friction transmission betweenthe cone and disc.

The friction idler 5I is axially adjustable between the friction coneand the friction surface of the stroboscope disc to vary the speed ofthe disc as required. To manually accomplish this adjustment, the roller5I is rotatably supported on a bracket 52, which bracket is supported inthreaded relation on an adjusting screw 53. The adjusting screw 53 isrotatably supported in suitable bearings on the base I2 and theoutwardly extending free end is provided with a crank handle 54. Thebase plate I2 has a radially extending opening 55 through which theroller 5I extends and frictionally contacts the disc 23, along whichdisc it may radially be moved by rotation of the threaded shaft 53 toprovide the desired speed control. Inthe embodiment shown in Fig. 2, thedriving elements of the transmission are retained in the requiredfrictional relationship by means of a compression spring 49a between thepivoted motor and the base I2. The compression of the spring isadjustable by means of suitable lock nuts as shown. A preferredconstruction for this purpose is shown in Fig. ll, and will be describedlater.

The bracket 52 supporting the friction idler 5I is provided with anelongated rod 56 of insulating material extending therefrom andadjustable therewith and having a tip extension 51 of current conductingmaterial, which tip, upon axial movement of said rod, progressivelyengages condenser contacts 58, 59, B0, and 6I (Fig. 4) of a suitableloading condenser in the tube circuit to thereby vary the capacity inthe stroboscope tube circuit in accordance with variations in speed in amanner hereinafter described in detail. The extension tip 51 is slidablysupported rin a bearing 62, which bearing vis insulated from the base I2and forms a terminal for a conductor 63 also forming part of thestroboscope circuit.

`By this means the capacity of a portion of the circuit mayprogressively be decreased relative to increased speed and vice versa.

The upstandng circumferential flange I5 on the synchronizer unit base I2is provided with spaced recesses 64 (Fig. '1) to accommodate discsupporting rollers 65, each roller having an annular groove 66intermediate its ends. A protractor ring 51 (Figs. 1, 2, and 7) issuspended in these grooves so as to lbe freely rotatable concentricallywith the stroboscope disc and the ring has a handle 68 for ease ofoperation whereby the protractor may readily be set to any desiredpoint.

At the top of the cabinet A is a casing containing a pair of rollers onwhich is wound a chart containing all necessary data with respect to thestandardized characteristics of various engines and distributors such asdwell-period. vacuum advance, automatic advance, and the like as appliedto various automobiles. 'Ii'he rollers are provided with knobs 10 sothat the chart may be moved to expose any required data through a window1I.

In operation, after a distributor has properly been inserted and securedin the supports, and the motor started, the arrow 3| rotates'adjacentthe inner edge of the protractor ring 51 and, upon the precise points inthe rotation of the distributor under test wherein the circuit breakerpoints separate, there is a succession of arrow flashes adjacent theprotractor ring, and the position of these flashes, as shown by the-illuminated arrow, clearly indicates the separation in degrees betweensuccessive circuit breaker interruptions. The protractor ring isgraduated in degrees and is adjustable relative to the position of thearrow flashes so that the zero indicia on the Vprotractor may be set inalignment with one of the fiash arrows and the distance betweensuccessive flashes of the stroboscope light may readily be read indegrees. Also any movement of the light arrows in response to sparkadvance or the like may easily be observed and read in angular degrees.

The number of lobes on the distributor cam determines' the number ofstroboscopic flashes which will occur upon each revolution of thedriveshaft. Thus, the six-lobe cam of the usual distributor of asix-cylinder engine causes the breaker points thereof to separate sixtimes for each revolution of the distributor shaft. providing six spacedflashes which appear as xed arrows separated by angles of sixty degreesrotation of the distributor shaft. In a distributor for a four-cylinderengine, four flash arrows would be separated at an angle of ninetydegrees, while for an eight-cylinder engine eight iiashes are separatedby an interval of forty-five degrees. The stroboscope flash tubeemployed may beof `standard character installed substantially asdiagrammatically shown in Fig. 2 so as to bodily rotate with the stubshaft I1.

The complete electric circuits for the stroboscopic device, the dwellmeter, and the tachometer are illustrated somewhat diagrammatically inFig. 8 and, by virtue of the circuit connections there shown, it ispossible either separately or simultaneously to make `all of the varioustests Without interference between the individual parts of theinterrelated circuits. This feature of the circuit connectionsillustrated in Fig. 8 constitutes an important part of the invention andis not believed to have heretofore been accomplished in the art. Whilepreferably a `single multiple-pole multiple-position switch, such, for

instance, as diagrammatically illustrated in Fig. 10, is utilized tovary certain of the circuit connections in order to provide for thetesting of four, eight, or six-lobe distributors, as desired, certain ofthe componentparts of this switch are indicated in the diagram (Fig. 8)as separately operable switches in order to simplify the showing of thecircuit connections. It will, of course, be understood that a pluralityof separately operable switches may be used in place of a singlemultiple-pole multiple-position switch, if desired.

Referring first to the right-hand portion of the circuit connectionsshown in Fig. 8, which portion constitutes the control for the neon tubeor stroboscope, it will be observed that the internal circuits of' theanalyzer are arranged for connection through suitable extensionconductors 12 and 13, having terminal clips 12a and 13a, to thedistributor D and the ground side of the engine EG, respectively.

The necessary energization for the stroboscopic circuits is provided bya six-volt battery 1d connected to energize the respective primarywindings of a spark coil 15 and of a power pack 1E;

The energization circuit for the spark coil 15 extends from the positiveside of the battery through the conductors |00 vand it, the primarywinding of the spark coil, the conductors |02 and |03, the extensionconductor l2, the distributor D, the extension conductor 13, theconductors |04 and |05, and by way of the analyzer ground connections AGto the opposite side of the battery.

The power pack 16 is of a type readily available upon the market andincludes a step-up transformer, the primary and secondary windings ofwhich are connected as shown to a doublepole double-throw vibratorelement 16a. 'I'he midpoint of the primary winding of the power packtransformer is connected, as shown, to the battery 16 through aconductor |06, and the vibrator element is connected to ground, asshown, to provide a suitable return circuit.

In the previously described circuit for the spark coil 15, it has beenassumed that the distributor has been removed from the engine andmounted on the synchronizer for operation thereby, but if desired thedistributor may be left on the 'engine and the speed of the stroboscopedisc synchronized with the engine speed. In this latter case the enginebattery which normally supplies the ignition system of the engine willbe in parallel with the battery 14 of the analyzer and the voltagesupplied to the analyzer circuits will therefore be unaffected.

The secondary side of the power pack 1t is connected as shown, through achoke coil 11 and a variable condenser 18, to one terminal of the gastube 29, and the opposite terminal of the tube is connected to theanalyzer ground so as to provide a proper return circuit. Also connectedto the secondary side of the power pack is a suitable condenser |01which latter serves as a reservoir or tank for the tube circuit. Whenthe tube 29 is tripped or ignited as hereinafter described,

' the condenser 18 immediately discharges therethrough, but the choke 11serves to block the condenser |01 from the tube circuit until after theflashing of the tube has terminated. Thus the discharge of the condenser|01 through the tube 29 is prevented, and the condenser |01 serves torecharge the condenser 18 preparatory to another flashing operation.

The power pack 16 is arranged to supply approximately 500 volts acrossthe terminals of the lib Iii

tube 29,'fand, inasmuch as a voltage of this magnitude is insufficientto cause breakdown of the tube resistance, an external trigger terminal19 is provided and is connected as shown through a conductor 31 andsuitable spark gaps 31a to the spark coil 15. The purpose of the sparkgaps 31a is to block out the oscillating voltage surges which follow theinitial high voltage surge utilized to cause a break-down flash of thetube 29.

It Will now be apparent thatopening of the breaker points of thedistributor D so as to interrupt the primary circuit of the spark coil1B produces a high voltage surge in the secondary which surge iseffective to cause breakdown of the tube 29 and flash a brilliant lightat the exact instant of break at the ignition points. Con sequently theflash is in exactly timed relation with the point action and the highvoltage surge on the trigger terminal 19 permits substantiallyinstantaneous discharge of the loading condenser 'i0 through the tube 29to accomplish the desired lighting of the tube.

The loading condenser 18 is so adjusted as to have a capacity ofapproximately two microfarads when in a position corresponding to slowspeed operation of the distributor and a discharge on the order of fiftyamperes in less than one-millionth of a second occurs through the neontube 29. The distributor speed may be varied over a wide range,preferably from R. P. M. to 2200 R. P. M., and, as the speed isincreased, the increased rapidity of the discharge through the tube 20requires that the capacity of the loading condenser be relativelydecreased to maintain proper voltage regulation of the power pack andprevent burn-out of the tube. Accordingly, the variable speed mechanism,as previously described, is arranged to vary the capacity of the loadingcondenser 18 in accordance with variations of the speed oi operation ofthe'stroboscope device.

As previously indicated, the stroboscope circuit, the dwell metercircuit, and the tachometer circuit in the motor analyzer of thisinvention are so combined in a single electric circuit that only onepair of connecting leads need be attached to the distributor undergoingtest, inA order to provide for any and all of the various tests. Thecircuit connections are suchithat the various instruments and testapparatus will respond only to the specific characteristics for whichthey are intended and will be unaffected by the electricalcharacteristics of the other circuits.

The tachometer testing circuit, as shown in the lefthand portion of Fig.8, comprises a milliammeter l, preferably graduated to read directly inR.` P. M. and adapted to be controlled by a tachometer relay having awinding |08 and a movable contact arm |09 arranged alternately to engagethe contacts ||0 and ||I as the winding is de-energized and energized,respectively. The winding |08 is connected as shown across the terminalsof the distributor D through a circuit which extends from the leadconductor 12 through the conductors |03, ||2, and H3, the winding |08,the conductors IH, H5, and H6, the contacts of the multiple-positionswitch H1, and by way of a conductor I8 to the lead con- -ductor 13.Thus, as the distributor contacts open .current is sufficient in lay, acircuit is completed `which extends from the contact through theconductors H2, IIB, and IIB, the contacts of the switch ill, the battery|20, which latter is preferably a one and one-half volt battery, aconductor lil, a second one and one-half volt battery |22, and theconductors i23 and |24, to one side ci a suitable condenser 83, theotherside of which is connected as shown to the movable relay contactH09. The condenser 03 is so related to the circuit in which it isconnected that it will receive a maximum charge each time the contact H0is closed, even though the contact remains closed for only an instant.Upon opening of the contact H0 and closure of the contact iii, a circuitis completed through which the condenser 03 may discharge, which circuitextends from the contact ill through the conductor H25, the contacts ofthe multiple-position switch.- iZii, the tachome ter milliammeter d, andby way of the conductors iti and 20 to the condenser 03, the other sideof which is connected, as previously stated, to the movable contact 00.

Thus, operation od the relay serves alternately to charge the condenserirom thel batteries itt and |22 and to discharge the condenser throughthe tachometer milliammeter il. Since the amount of charge accumulatingon the coardenser 03 does not depend upon the duration oi the engagementof the contacts 900 and. H0, the average current supplied to thetachometer is independent of the duration of contact and is directlyproportional to the speed of operation of the tachometer relay. It willaccordingly be seen that the tachometer will give a direct reading ofthe speed at which the distributor is operating.

The dwell meter 5 is connected, as shown, in

Acircuit with a plurality of resistors itt, iti, ltr,

and |33; a pair of rectifier elements it and itt, which are preferablyof the copper disc type; a pair of multiple-position switches lll anditt; and a one and one-half volt battery |120. This circuit provides aWheatstone bridge having the arms A, B, C, and D, respectively, thereofconnected at the nodes or vcorners M0, itl, liti, and

|43, respectively.

The dwell circuit thus produced is adapted to be energized from the sameconductor leads 'it and 13 as connect the tachometer circuit to thedistributor, and the energization circuit, which will be hereinafterdescribed, is connected by means of the conductors H6 and |40,respectively, to the nodes |42 and |43, the dwell meter 5 beingconnected as shown across the bridge nodes |40 and |4|. In order tosupply a substantially hat-topped voltage wave to the dwell bridgecircuit, a suitable inductance Band a condenser |46 are connected inseries circuit with each other across the distributor leads and inparallel circuit relation With the relay winding |08, and the conductors||6 and |64 previously referred to are connected to opposite sides ofthe condenser |46 as shown.

ductors 12 and 13 and accordingly no voltage is' applied to the dwellcircuit from these leads. Under these conditions, a current is caused toiiow through the dwell meter by the battery |20, which magnitude tocause the indicating needle of the dwell meter to occupy a positioncorresponding to its maximum reading. This circuit may be traced fromthe positive side of the battery through the multiple-position switch|38 and the rectifier |34 in the arm D of the bridge, from the nodepoint |40 throughthe dwell meter 6to the node point Mi, and byrway ofthe resistor |32 in the arm C oi the 'bridge and the multiple-positionswitch ii'i to the negative side of the battery. Small additionalcurrents will, of course. flow through the resistors l30 and |3i and byway of the conductor M4, the indue tance |05, the conductorV l i3, therelay winding |03, and the conductors iid, iii, and llt to the nodepoint 43 and through the switch Eil to the negative side of the battery,but these small currents have no effect on the operation ot the dwellmeter. Likewise, there is a tendency for current to flow through thefeed-back circuit including the rectifier |30 and the balancing resistor|03, but the high resistance of the rectier i3d to current flow in thisdirection will prevent any appreciable current from passing through thisfeed-back circuit.

As soon as the distributor points open during operation oi thedistributor D, a voltage will be applied to the parallel circuitcomprising the relay winding |108, the inductance ldd, and the condenserit and a voltage equal to that Vbuilt up across the condenser will 'beapplied to the nodes M2 and 'itt of the Wheatstone 'bridge' circuit.This voltage may vary in magnitude trom ap proximately il/s volts, whichcorresponds to the ignition voltage during cranking of the engine, tothe maximum ignition voltage of 6 or l2 volts depending upon the voltageof the engine battery or test batteri/,being used. In order to provideproper operation of the dwell meter over this range of voltage, theresistors |30, liti, and itt in the arms A, B, and C of the bridgecircuit are so correlated with the back; resistance of the rectifier i3dand the internal resistance oi the battery m0 in the arm D of the bridgethat substan tially zero voltage will be produced across the bridgenodes |40 and iti. Consequently, zero current will flow through thedwell meter during the time that the distributor points are open and theneedle of the dwell meter will tend to return to its zero position. Theproportionate periods of time during which the dwell meter is thussubjected to maximum energization and to zero energization depend uponthe dwell of the `distributor cam and accordingly the meter will give anindication of these dwell periods..

In order to prevent fluctuation of the indicating needle on the dwellmeter, a suitable -condenser |50, which may be on the order of a 2,000microfarad condenser, is connected directly across the terminals of thedwell meter'so vas to cause the indicating needle to assume a steadyposition corresponding to the average current flow and to theproportionate periods of time during which the dwell meter is energizedand de-energized. Preferably the dwell meter is graduated to readdirectly in degrees so as to facilitate ready determination of the dwellperiod.

The feed-back circuit comprising the resistor |33 and the rectifier |35serves to provide substantially zero voltage conditions across the nodepoints |40 and |4| over the complete voltage range, this feed-backcircuit being connected in 1 parallel with the bridge arm C and aportion of the bridge arm D, and the combined resistance of thesecircuits being so correlatedwith the resistance in the bridge arms A andB as to permit a balanced condition to exist over the desired voltagerange. The resistor C is preferably formed of a material having suitabletemperature coeicient to provide temperature compensation for thebridgef circuit and prevent changes in ambient tetnperature fromenacting unbaiance of the bridge.

the

. The multiple-position switches H1 and |38 in v spectively. Themanually operable push-buttonr switch ISI, shown in Fig. 8 as beingconnected between the negative terminal of the battery |20 and thenegative terminal ofthe tachometer I, may be used to connect thetachometer directly across the batteries I 20 and |22 for calibrationpurposes. l

As previously stated, the present invention may be used tosimultaneously test the various functions of a distributor. and thetachometer, dwell meter, stroboscope, and vacuum brake mechanism maysimultaneously 'be operated for comparative readingaso as to properlyindicate the true operation 'of the distributor under test. In thisconnection, the chart previously referred to may be employed to show therequired instrument readings for each phase of distributor operation.

The operation of the device, particularly the circuit embodiment shownin Fig. 8 is used, may be as follows:

First, the control switch, or switches, are adjusted to the four, -six,or eight-lobe position, as required by the distributor under test, thedistributor to be tested is installed as previously'described, and thestroboscope tube circuit is properly connected so that each break of thecircuit breaker points in the distributor may properly aifect thecircuit. The stroboscope disc is then rotated at a predetermined speedby adjustment of the handle 54 and this speed is indicated by' thetachometer t. Simultaneously, --the dwell meter, which is unaiiected byoperation of the tachometer and may be simultaneously operatedtherewith, will indicate whether or not the angle of cam dwellcorresponds to that specified on the chart.

Most distributors for internal combustion engine/s are provided with twomeans for changing the amount of spark advance. y means is the automaticadvance, which is ordinarily va simple centrifugally operated governorarranged to advance the spark as the engine speed increases. Thisarrangement vprovides for a gradual'advance of the spark to insuremaximum performance of the engine at higher speeds.

The second means of spark advance is the vacuum advance" or vacuumbrake." The operation of this is controlled by the amountvof vacuumexisting in the engine's intake manifold at any particular moment andvaries with changes in said vacuum i. e., upon sudden accel- 'erationintake manifold vacuum is lost and this automatically causes a retardingof the engines spark. By retarding the engine spark in this manner,knocking or improper detonation in the engine is prevented.-

It is, therefore, particularly important that these two spark advancemeans be testedand ad- Justed in accord with factory speciiications.

` vacuum pump by operation The present vinvention is particularlyadapted to such testing and adjusting and provides means whereby eachmay be tested independently of the other to insure that the distributorconforms to factory specications and operates as required for'maximummotor performance. v

To provide vacuum in a controlled manner to the distributor under test,if the amount of vacuum is to be controlled by the vacuum pump motorspeed, the operator may start and control the |58 as shown, or a simpleon-01T switch may be used for the vacuum pump motor and the amount ofvacuum may be regulated by a vacuum bleeder valve in a mannerhereinafter described. By this means, there is applied to the vacuumadvance or the vacuum brake mechanism of the distributor under testtheamount of vacuum which, as indicated by the chart. is the propervacuum for the test to be made.

The present invention permits both automatic advance and vacuum advanceto be independvently checked and adjusted as follows:

As changes in motor speed or distributor speed cause similar changes inthe amount oi automatic l advance, in order to check and adjust thevacuum advance independently of the automatic advance, the distributoris 'ilrst placed in operation at a uniform speed. The uniformity of thespeed may be checked throughout this test by the tachometer '4, as anysubstantial variations in angular degrees on the stroboscope protractorring indicate a defective automatic advance The ilrst of these ,l

mechanism, worn bearings, a tendency for the stroboscope arrow to jumpirregularly at dinerent points about the protractor ring will indicate"point bounce" caused by improper spring tension, worn pointer armbearings. cam contacting surfaces, or the like.

With the distributor operating at a constant speed, as above,`the vacuummay be applied to the vacuum advance or brake control in increasingamounts as indicated on vacuum gauge T and in accordance with therequirements of the data chart. The actual amount of spark advance orretard obtained at each vacuum setting is indicated by the stroboscopein angular degrees. This amount may be checked with the data uponl thechart to insure that the distributor is performing exactly according tothe standards required for a maximum motor performance.

The proper performance of the vacuum control advance or brake mechanismis indicated by a change of position of the illuminated stroboscopepointer with respect to the protractor. The precise amount in angulardegrees of such change may accurately be read during actual operation ofthe distributor. The chart indicates the required amount of change forvarious readings. VAs the above test is made with the distributorrunning at a constant speed. as indicated by the tachometer, theautomatic advance mechanism does not operate to inuence the stroboscopedisc reading. This reading, therefore. correctly represents the actualamount of advance or retard provided by the vacuum advance mechanism.

Of course,l any change in cam dwell during the above test maysimultaneously be noted.

In order to check the operation of the "automatic advance mechanism, thevacuum pump may be disconnected and the distributor driven at theslowest speed at which it is intended to operate. At this point there isno advance of v the spark. By means oi' the handle 68, the prooftherheostat switch etc. Furthermore,

tractor ring may be adjusted so that each stroboscope ash is positionedopposite a zero point on the protractor ring. Thereafter, by operationof speed control vhandle 51|, the distributor speed is increased instages as called for by the data chart to its maximum operating speedand the amount of automatic advance ateach stage is accurately indicatedby the shifting of the stroboscope pointer a certain number of angulardegrees over the protractor ring. When the distributor is operatingproperly, the number of angular degrees of such shift corresponds to thenumber of degrees indicated on the data chart for such speed and anydeviation from the specifications of this chart indicates a conditionrequiring correction.

In all of the above, i't'will be apparent that any deviation in dwellangle is also indicated simultaneously with the other readings.

In some cases, it is desirable to eliminate one of the meters shown inFig. 8 and to use a single meter as a combined tachometer and dwellmeter, in which case the meter is preferably provided with a singlepointer operating over two scales, one scale for the tachometer readingsand the other for dwell meter readings. The diagram shown in Fig. 9illustrates a circuit arrangement for use in connection with a singlemeter. In this circuit a combined tachometer and dwell meter |52 is usedand connected in the circuit as illustrated. The circuit issubstantially identical with that shown in Fig. 8, with the exceptionthat multiple-pole three-position switches |53 and |55 are so connectedin the circuit that, by suitable manipulation of the switches, the meter|52 may selectively 'be connected to either the tachometer or dwellmeter circuit, as desired. The circuits are, of course, interconnectedat some points and each functions in the same manner as previouslydescribed; however, it is necessary to operate the switches B53 and |5||to obtain the required reading from the meter.

In the embodiment shown in Fig. 9, the conductors i l2 and ||8 may, ofcourse, be directly connected to the flexible terminals 12 and 13 in thesame manner as shown -in Fig. 8. However, for convenience, theseconductors are shown connected to the socket terminals of a so-calledcinch-socket portion |55 of a connector, so thatsuitable terminals fromthe synchronizing circuit conductors |02 and |04 (Fig. 8) may be pluggedtherein.

As previously stated, a suitable chart containing all necessary datawith respect vto the standardized characteristics of variousdistributors is supported on a pair of rollers at the top of the cabinetA. Suitable electric lights |56 (Fig. 9) are positioned in the cabinetadjacent the rollers in order to illuminate the meters. These lights aregrounded and also connected to the socket |55 by means of a conductor|51 and any suitable battery connection may be made when the circuitplug is inserted in the socket |55..

The vacuum pump 8 previously mentioned is provided with a suitable motorfor driving the pump, and the amount of vacuum may be controlled byvarying the speed of the motor by rheostat switch |59 or by a bleedervalve ISI. Switch |59 serves to connect the motor circuit to theconductor |51 and the opposite side of the motor circuit is grounded asshown. Of course.

rheostat switch |55 may be asimple on-off switch if desired, and theamount of vacuum can be controlled solely by` adjustment of the lbleedervalve. A suitable power source maybe uum control. A pressure conduit |62is provided with a coupling |62a which may be connected to the usualvacuum brake or advance connection of the distributor under test bymeans of a flexible conduit |63 (Fig. 1).

Although the vacuum pump control and the meter light circuit are shownonly in Fig. 9, it will be understood that they' are also used inconnection with the embodiment shown in Fig. 8.

Figs. i1, 12, and i3 illustrate a preferred form of cone drive for usein the transmission for driving the :troboscope friction disc 23illustrated in Fig. 2. The preferred form shown is an automatic clutchand friction pressure control which forms that portion of thetransmission which is directly connected to the motor. In thisconstruction the motor is not suspended on the plate it as previouslydescribed, but instead a suitable motor Ma is supported on a bracket ittand is preferably resiliently mounted thereon by means oi a pad M55 cisuitable cushioning material. The bracket iiii is rigidly supportedbeneath the plate it so ,as to support the motor in substantially thesame position as previously described. The bracket may be an integralpart of the plate or may form any suitable iixed portion of the frame ofthe device. In this preferred construction the friction cone 5ta isslidably mounted on the motor shaft and, when the motor is at rest, thecone stands substantially in the position shown in full lines in Fig.il, that is, retracted out of contact with the friction roller 5|.

Automatic means is provided so that, when the y motor attains apredetermined speed, the cone is clined surfaces llt.

automatically advanced substantially to the position illustrated bydotted lines and into driving engagement with the friction roller 5i.The mechanism for accomplishing this result comprises a tubular motorshaft extension 66 and a rotor itl, both of which may be secured to theshaft by means of a setscrew |58. The face of the rotor itl is providedwith radial grooves it@ the outer ends of which are provided with in-The cone 5M is provided with an elongated hub |1| and is slidablymounted on the tubular shaft extension |56 and. on a plurality ofoutwardly extending pins or guide rods |12 which latter are secured inthe rotor |61 for driving the cone. A spring |68 in the tubularextension |56 normally tends to move the cone outwardly and into contactwith the friction roller 5| and to retain a suitable pressure thereon. i

A steel ball |13 is mounted in each of the radial grooves |69 in therotor and normally is in the retracted position shown adjacent the hubof the friction cone. The balls |13 are retained in their respectivegrooves by means of a sheet metal disc 14, which disc is ormedto[provide radial grooves |15 therein. These radial grooves |15 in thesheet metalV disc are complementary to the radial grooves |69 in therotor. The disc |14 is slidably mounted on the hub |1| of the cone andis normally retainedl in the position illustrated by means of a.relatively strong compression spring |16 which latter is undercompression between the disc and a cover member |11, the cover memberbeing secured to the rotor |61 by means of screws |18. The compressionof the spring |16 is sufficient to normally retain the provided throughthe socket |55 when the coni cone 80a in the retracted position shown byfull -lines against the compression of the spring |88.

However, when the motor reaches a predeterminedspeed, the balls |13 aremoved outwardly by centrifugal force into the inclined ends of thegrooves |89 land thereby move the disc |14 substantially tothe positionshown by dotted lines, this permits the compression spring |68 tosimultaneously move the cone into resilient friction contact with thefriction roller 81. 'I'he amount of pressure with which the cone ismoved outwardly depends only upon the strength of .spring |88 and isindependent of the load and of the motor speed. f

A split ring |19 is mounted in afcomplementar annular groove in the hub|11 .of .the fric' y speed of the motor' tion cone so that, when the isreduced, the projecting portion of the ring is engaged by the disc |14and the cone is moved rearwardly by the spring |18 and against thecompression of spring |88. By this means the cone 50a. is retained in.resilient frictional contact with the friction wall 5| duringpredetermined operating speeds of the motor and, as soon as the speed issuiliciently reduced, the balls |83 are forced back to their normalposition by means of the spring |16 and the cone is withdrawn fromdriving contact with the fric-- tionv roller.

The present invention is adapted for use with any internal combustionengines and is of particular use in commotion with the testing andadjustment of engines in automobiles, airplanes, tanks, boats, trucks,etc., and particularly where such engines must be adjusted to securemaximum performance over a wide range of speeds and operatingconditions.

In the present disclosure, the invention has..

been shown applied to internal combustion engines wherein combustion iseffected by means However, it will be arp-S4 parent that the hereinrecited testingzand adof an electrical spark.

justing features of this invention may be employed in conjunction withDiesel engines and the like upon the modification of the various partshereof to assemble the necessary information from the engine under test.

It is intended, of course, that the invention should not be limited tothe specific embodiment or embodiments disclosed herein, sincemodifications may be made, and it is contemplated, therefore, by theappended claims to cover any such modifications as fall within the truespirit and scope of this invention.

Having thus described this invention, what is claimed and desired to besecured by Letters Patent is:

1. In a stroboscopic synchronizer, a base plate, an outwardly extendingstub shaft rotatably supported in said base, a friction disc on saidshaft, means for supporting adistributor substantially in axialalignment with said shaft, stroboscopic means rotatable in synchronismwith said disc comprising an indicator whose indication is determined bythe make and break of a-dis'tributor circuit a flexible coupling forsecuring said stub shaft `to the distributor shaft, a reversibleconstant speed motor pivotally supported on the back of said base, withits axis bisecting the axis of but angular thereto, a. friction cone onthe motor shaft with its friction surface parallel with the'frictionsurface of said disc and its apex directed outwardly thereof, a frictionidler roller between said friction cone and said disc and extendingthrough said base, manually tion roller in said radial rotatable insynchronism with said disc, comprising an indicator whose indication isdetermined by the distributor circuits-:aid base plate having a radialopening below said disc, a constant speed motor pivoted on the back ofsaid base above the axis of said disc for swinging adjustment of saidmotor in the plane of the axis of said. discv buttransversely thereof, acone friction wheel on said motor shaft with its friction contact linesubstantially parallel with the friction .surface of said disc and itsapex substantially in .alignment with the periphery of said disc, africopening and in frictional driving relationship between said cone andsaid disc, means for manually adjusting said roller radially of saiddisc and cone, and means for reslliently tensioning said cone againstsaid roller. 3. In a synchronizer of the character de scribed,anangularly supported base plate having a rotatable stroboscope discpivotally mounted on the outside of said base with its axissubstantially vertical thereto and with its innerside having a frictionsurface, a motor supported on the inner side of said base with its axissubstantially horizontal and intersecting the axis of said disc, afriction cone on the shaft of said motor with its apex substantially inalignment with the lowest peripheral margin of said disc, a frictionidler between said disc and said cone and supported on said plate foraxial adjustment radially of .said cone and disc, and means foradjustably tensioning the friction surfaces.

4. A stroboscopic vsynclironizer comprising a base, a rotatable disc onsaid base, a power source, a variable speed transmission between saidpower source and said disc. a pointer rotatable with said disc, aprotractor around the path of said pointer and rotarily adjustablerelative to said pointer, a gas ash tube positioned to momentarilyilluminate said arrow in any position of rotation, means for drivinga'distributor in timed relation to said disc, an electrical circuitassociated with said distributor and said tube to ash said tube in timedrelation with the operation of the breaker points of said distributor,said circuit including a loading condenser for delivering a momentaryhigh break-down volt age discharge to said tube, and automatic means tovary the capacity of said condenser in accordance with variations in thespeed of said disc.

5. In a distributor testing stroboscope, the combination with arotatable pointer, means for driving a distributor and said pointer invariable timedrelation, and a gas tube for momentarily illuminating saidpointer in timed relation to the operation of the breaker points of saiddistributor, of an electrical circuit associated with said distributorand said tube, said circuit including means for impressing a highpotential across the electrodes vof said tube, said potential beinginsuflicient to break down the resistance of said tube, means controlledby said distributor to momentarily reduce the resistance of said tube intimed relation to the operation of the breaker points of saiddistributor to thereby enable a momentary surge of said high potentialto flash said tube, and automatic means to vary .aid high potential inaccordance with the speed of said pointer and distributor.

` I 6. A stroboscope comprising a rotatable pointer, a protractoradjustable around said tube is reduced, an external trigger gridadjacent said tube between the tube electrodes, means controlled by thebreaker points of said distributor to intermittently and| momentarilycreate a high potential on said trigger grid in timed relation to theoperation of said breaker points'so that said loading condenser willsimultaneously discharge through, and flash, said tube, means to varythe speed of said pointer and distributor, and automatic means to varythe capacity of said loading condenser in accordance with variations ofspeed of said pointer and distributor.

7. Ina distributor tester, a stroboscope disc,

means to support a distributor, a power source,

a variable speed transmisison for driving said disc and said distributorin synchronism over the speed range of said transmission. saidtransmission including a friction cone andra friction roller betweensaid power source and said disc, said cone being normally out of contactwith said roller, and means to automatically frictionally contact saidcone and` said disc when said motor attains a predetermined speed.

r8. In a distributor tester, a stroboscope disc, means to support a,distributor. a power source, a variable speed transmission for drivingsaid disc and said distributor in synohronism over the speed range ofsaid transmission, said transmission including a friction cone and afriction roller between said power source and said disc, said cone beingnormally out of contact with said roller, means to automaticallyfrictionally contact said cone and said disc when said motor attains apredetermined speed, said last means comprisingL a driven shaft on whichsaid cone is slidably mounted for movement toward and from said roller,a first resilient means normally tending to advance said cone into-frictional contact with said roller, a second resilient means normallymaking said ilrst resilient means -ineffective, and a. centrifugallycontrolled means to make said second resilient means ineffective toprevent advance of said cone.

- VIVIAN L. WESTBERG.

ARTHUR N. NILSON. VERNON C. WESTBERG.

